LKCANORA.] LECANO-LECIDEET. 391 



polari-bilocnlar, 0,011-15 mm. long, 0,006-8 mm. thick. Cromb. 

 Grevillea, xviii. p. 46. Placodium chalybwum Mudd, Man. p. 134 ; 

 Cromb. Lich. Brit. p. 46 ; Leight. Lich. Fl. p. 179, ed. 3, p. 165. 

 Rirmdia chalybcea Duf. in Fr. Lich. Eur. (1831) p. 125. Brit. Exs. : 

 Cromb. n. 59. 



Easily recognized by the colour of the thallus, which is somewhat 

 thickish, small or considerably expanded, occasionally somewhat lobed or 

 lobato-crenate at the circumference. The apothecia are numerous and 

 crowded, becoming, when moistened, turgid, somewhat prominent, and 

 livid-brown. 



Hab. On calcareous rocks in maritime and mountainous districts. 

 Distr. Local in S.W. andN. England, N. Wales, and the Central Gram- 

 pians, Scotland. B. N. : Babbicombe, Devonshire ; Llanymynech Hill, 

 Shropshire ; Great Orme's Head, Carnarvonshire ; Penhill, Yorkshire ; 

 Craig Tulloch, Blair Athole, Perthshire. 



55. L. variabilis Ach. Lich. Univ. (1810) p. 369. Thallus 

 determinate, adnate, thinnish, diffracto-areolate, greyish-brown or 

 lurid-grey (K-f violet), usually limited by a thin blackish hypo- 

 thallus. Apothecia submoderate, slightly prominent, plane or con- 

 vex, black, subpruinose (K ) ; the thalline margin entire, usually 

 white-suffused ; spores broadly ellipsoid, polari-bilocular, 0,013-16 

 mm. long, 0,007-0,010 mm. thick. Cromb. Grevillea, xviii. p. 46. 

 Placodium variabile Leight. Lich. Fl. p. 179, ed. 3, p. 165. Lichen 

 variabilis Pers. in list. Ann. (1794) p. 26. 



Similar to the preceding species, but distinguished by the thinner, 

 darker non-effigurate thallus, the more prominent apothecia, and the 

 rather larger spores. In the British specimens the hypothallus is only 

 sparingly visible. The apothecia, which when moistened are livid-brown, 

 are usually numerous, at times crowded and somewhat angulose. 



Hab. On calcareous rocks in upland hilly situations. Distr. Seen only 

 from W. and Central England, and (Jide Leight.) N.W. Ireland (Conne- 

 mara, Galway). B. M. : Bathampton Downs, Somersetshire ; Grove 

 Lane, Cirencester, Gloucestershire ; Cunning Dale, Buxton, Derbyshire ; 

 Llanymynech Hill, Shropshire. 



Yar. /3. ecrustacea Nyl. ex Cromb. Grevillea, xviii. (1889) p. 46. 

 Thallus indistinct. Apothecia small, lecideoid, subinnate, at 

 length immarginate ; otherwise as in the type. Placodium variabile 

 var. ecrustacea Nyl. Lich. Scand. (1861) p. 139. P. Agardhianum 

 Hepp (non Ach.), Leight. Lich. Fl. ed. 3, p. 165. 



Differs in the absence of a thallus and in the character of the apothecia. 

 But for the form of the spores it might be taken for a Lecidea. 



Hab. On calcareous rocks in maritime and upland districts. Distr. In 

 S.W., N.W. England, and S. Wales. B. M. : Anstey's Cove, Torquay, 

 S. Devon ; Bathampton Downs, Somerset ; Tenby, Pembrokeshire ; 

 Lamplugh, Cumberland. 



